Stinger or strut.

[Ron Olson]

Go for it John.

We had this talk elsewhere between John, myself and another member in here and he brought up some good points that I haven't thought of but now I understand.

The problem involved stinger struts and why we were having problems with handling, mostly chine-walking.

I'll let the "Perfesser" take it from here................

 

[mtruex]

Go for it John.We had this talk elsewhere between John, myself and another member in here and he brought up some good points that I haven't thought of but now I understand.

The problem involved stinger struts and why we were having problems with handling, mostly chine-walking.

I'll let the "Perfesser" take it from here................

would cutting the stinger shorter help this problem?

 

[Joe Warren]

How about we talk about how far from the transom do we position the prop? That is probable the best question here on struts. Height, angle, etc.

On Most of the Speedmaster hardware the Length of the STRUT Mounting brackets were estabilished after you seen where the rudder was mounted. Some hulls liked a longer than 2 inch rudder mounting bracket..... Many of the speedmaster set ups. The leading edge of the prop & the leading edge of the rudder blade were in line with each other. This prevents the prop wash from being thrown into the Rudder blade...... if the hardware was set up like this IN -LINE the prop wash is just aft the rudder blade. This goes for many diff boats especially the ones the mfger has not written any instructions on the hardware type or Placement of hardware. P.S. Strut vs Stinger... Some boaters believe there is a Vortex Around the prop anytime it is running in the water. the Singer does not have a vertical bracket for the vortex to push on (prop walking the boat). But a Extended Strut will do the same thing........ Joe w

 

[Andy Greene]

For my Seaducer I followed the given measurements and suggested hardware and it works well. Has someone found a better way to skin a cat-seaducer mono in this case- Using a stinger that works well on say a 40 or 60 Seaducer ??

Somewere I saw a REALLY trick adjusting device that worked on a strut- gave VERY accurate strut adjustments in height and pitch- just cant remember were !!!! <_<

What kind of effect would we have if the rudder was run even further in(closer to the transom) than than in-line idea ??(leading edge of rudder with leading edge of prop surface) Would the boat be tighter due to the rudder being closer to the transom ?

What about sharpening the bottom of the rudder blade to a sharp edge rather than a flat bottom? benefits? downsides?

Andy

 

[John Finch]

For my Seaducer I followed the given measurements and suggested hardware and it works well. Has someone found a better way to skin a cat-seaducer mono in this case- Using a stinger that works well on say a 40 or 60 Seaducer ??
Somewere I saw a REALLY trick adjusting device that worked on a strut- gave VERY accurate strut adjustments in height and pitch- just cant remember were !!!! <_<

What kind of effect would we have if the rudder was run even further in(closer to the transom) than than in-line idea ??(leading edge of rudder with leading edge of prop surface) Would the boat be tighter due to the rudder being closer to the transom ?

What about sharpening the bottom of the rudder blade to a sharp edge rather than a flat bottom? benefits? downsides?

Andy

I have found a profound difference in location of rudder on the transom affecting almost every aspect in trimming the boat. The 77 mph pass KP and I did with the 20 mono at record trials is a good example. The rudder was used to tune the boat for the correct ride. The distance from the transom was paramount in trimming the boat because there were no trim tabs. If I told you the strut length you would say...........no way. Don't even ask. As for todays heat racing boats You are totally correct on the rudder location as far as distance from the transom. The closer the rudder is to the transom, the more it holds the bow down. As you move the rudder away from the transom the nose ( bow) becomes lighter on the water. As for the bottom of the rudder...........if it's flat it can lift the boat like a riding surface, so rounding it off is usually a good idea.

John

 

[John Finch]

How about we talk about how far from the transom do we position the prop? That is probable the best question here on struts. Height, angle, etc.

On Most of the Speedmaster hardware the Length of the STRUT Mounting brackets were estabilished after you seen where the rudder was mounted. Some hulls liked a longer than 2 inch rudder mounting bracket..... Many of the speedmaster set ups. The leading edge of the prop & the leading edge of the rudder blade were in line with each other. This prevents the prop wash from being thrown into the Rudder blade...... if the hardware was set up like this IN -LINE the prop wash is just aft the rudder blade. This goes for many diff boats especially the ones the mfger has not written any instructions on the hardware type or Placement of hardware. P.S. Strut vs Stinger... Some boaters believe there is a Vortex Around the prop anytime it is running in the water. the Singer does not have a vertical bracket for the vortex to push on (prop walking the boat). But a Extended Strut will do the same thing........ Joe w

Joe,

I have run the seaducer hardware as you stated on all four of my seaducers and the boats tended to be non linear in the turns. They darted or tightened up too fast at the apex of the turn. I don't know if extending the rudder further back from the transom would help or not on those boats because of the design. It may be that Jerry put the rudder there for the amount of affect it has in holding the bow in the right attitude. I don't know. On other boats I have found that moving the rudder further from the transom will put less pressure on the front of the boat in the turns and give better leverage in the distance from the turn fin to the rudder for a more controlled turn. When I was running Twin Craft I always suggested the rudder leading edge be just behind the trailing edge of the prop. The prop blast would hit the rudder when the boat travelled down the straightaway and the deflection off the rudder aided in fighting prop walk. Then, when the rudder turned to the right to make a turn, the prop wash was allowed to go to the right to be unobstructed for the turn and it took little rudder to make a nice sweeping turn. I also found that having the rudder in front of the prop tended to make the rudder less responsive and sometimes of little use against the turnfin and prop. When I experimented with twins I used the rudders just to the outside of both props like I just explained to control the propwash on the outside of both props and it was the only scenario that gave linear turns.

As for the extended strut..........I found that out by mistake in 1982 when I set a 60 mono oval record and the boat had no prop walk. It took me a while to understand the vortexxxxx thing because it was the only thing that made sense when this was the first mono I ever had that did not prop walk. I had used an Octura steel strut and reversed the strut to get the prop further from the tramson. Little did I know that was the beginning of the no walk strut. All it takes is about an inch of straight tubing behind the strut for the water to collapse back and enter the top half of the prop.

 

[John Finch]

Go for it John.We had this talk elsewhere between John, myself and another member in here and he brought up some good points that I haven't thought of but now I understand.

The problem involved stinger struts and why we were having problems with handling, mostly chine-walking.

I'll let the "Perfesser" take it from here................

would cutting the stinger shorter help this problem?

MT,

As for the chine walking thing. That is resolved mostly by mounting the stinger to the right of centerline to lift the right side of the boat. The prop lifts the hull as well as pushes it, so lifting more on the right side of the boat helps to keep the boat from rolling to the right. When you get the right amount of distance to the right of centerline the chine walk goes away.

 

[Andy Greene]

How about we talk about how far from the transom do we position the prop? That is probable the best question here on struts. Height, angle, etc.

On Most of the Speedmaster hardware the Length of the STRUT Mounting brackets were estabilished after you seen where the rudder was mounted. Some hulls liked a longer than 2 inch rudder mounting bracket..... Many of the speedmaster set ups. The leading edge of the prop & the leading edge of the rudder blade were in line with each other. This prevents the prop wash from being thrown into the Rudder blade...... if the hardware was set up like this IN -LINE the prop wash is just aft the rudder blade. This goes for many diff boats especially the ones the mfger has not written any instructions on the hardware type or Placement of hardware. P.S. Strut vs Stinger... Some boaters believe there is a Vortex Around the prop anytime it is running in the water. the Singer does not have a vertical bracket for the vortex to push on (prop walking the boat). But a Extended Strut will do the same thing........ Joe w

Joe,

I have run the seaducer hardware as you stated on all four of my seaducers and the boats tended to be non linear in the turns. They darted or tightened up too fast at the apex of the turn. I don't know if extending the rudder further back from the transom would help or not on those boats because of the design. It may be that Jerry put the rudder there for the amount of affect it has in holding the bow in the right attitude. I don't know. On other boats I have found that moving the rudder further from the transom will put less pressure on the front of the boat in the turns and give better leverage in the distance from the turn fin to the rudder for a more controlled turn. When I was running Twin Craft I always suggested the rudder leading edge be just behind the trailing edge of the prop. The prop blast would hit the rudder when the boat travelled down the straightaway and the deflection off the rudder aided in fighting prop walk. Then, when the rudder turned to the right to make a turn, the prop wash was allowed to go to the right to be unobstructed for the turn and it took little rudder to make a nice sweeping turn. I also found that having the rudder in front of the prop tended to make the rudder less responsive and sometimes of little use against the turnfin and prop. When I experimented with twins I used the rudders just to the outside of both props like I just explained to control the propwash on the outside of both props and it was the only scenario that gave linear turns.

As for the extended strut..........I found that out by mistake in 1982 when I set a 60 mono oval record and the boat had no prop walk. It took me a while to understand the vortexxxxx thing because it was the only thing that made sense when this was the first mono I ever had that did not prop walk. I had used an Octura steel strut and reversed the strut to get the prop further from the tramson. Little did I know that was the beginning of the no walk strut. All it takes is about an inch of straight tubing behind the strut for the water to collapse back and enter the top half of the prop.

John , I have found with Jerry's boats you really have to shorten servo travel and rate to the rudder regarding right input. That and a shorter rudder blade, will take the darty turns out of the boat. Mine carves smooth unless I have to MAKE it dart to avoid something.

On that note what kind of effects does a shorter and thinner rudder have. What combination of blade area and lenght works best for what application ?? Saws versus heat racing trim.

From the sounds of your responses I would say the record boat had a VERY long strut in reference to distance from rudder leading edge ?? ?

 

[John Finch]

Andy,

Should have been there man. The water was great. I think everyone would say a smaller and shorter rudder is the way to go because it's less drag. I feel that a wider rudder might sometimes be better than having to use trim tabs. I also think if your boat requires say 1/4th inch of left rudder to make the boat track straight. then a 1/4 inch rudder width with the right side of the blade parallel to the keel is better than a 1/8th thick blade that leaves a vapor trail on the right side of the rudder. And since the amount of rudder has a great deal with keeping the prop from dragging the transom to the left, it takes a certain amount of rudder to keep the boat tracking straight. What I try to keep in mind is that without a rudder the boat would do a big right hand turn. How much rudder you add to that equasion will directly affect how much control you have in keeping the boat in a straight line going down the straightaway.

So, in the last hour we have talked about rudder location as far as distance from the transom and how it trips the boat into pushing the bow down or lets the bow fly free, Thickness, rounding the bottom, position in relation to prop, How it can be a trim tab, How making travel less sensitive can prevent non linear turning, and how different setups work on different boats. That's pretty good. A lot of good input. There is also shape of rudder, pivot point, kicking it back vs tucking it in, tilting it to the right, and distance from the keel to the chine line. Who would have thought so much could be controlled by a simple rudder or combination of rudders.

 

[Andy Greene]

Andy,Should have been there man. The water was great. I think everyone would say a smaller and shorter rudder is the way to go because it's less drag. I feel that a wider rudder might sometimes be better than having to use trim tabs. I also think if your boat requires say 1/4th inch of left rudder to make the boat track straight. then a 1/4 inch rudder width with the right side of the blade parallel to the keel is better than a 1/8th thick blade that leaves a vapor trail on the right side of the rudder. And since the amount of rudder has a great deal with keeping the prop from dragging the transom to the left, it takes a certain amount of rudder to keep the boat tracking straight. What I try to keep in mind is that without a rudder the boat would do a big right hand turn. How much rudder you add to that equasion will directly affect how much control you have in keeping the boat in a straight line going down the straightaway.

So, in the last hour we have talked about rudder location as far as distance from the transom and how it trips the boat into pushing the bow down or lets the bow fly free, Thickness, rounding the bottom, position in relation to prop, How it can be a trim tab, How making travel less sensitive can prevent non linear turning, and how different setups work on different boats. That's pretty good. A lot of good input. There is also shape of rudder, pivot point, kicking it back vs tucking it in, tilting it to the right, and distance from the keel to the chine line. Who would have thought so much could be controlled by a simple rudder or combination of rudders.

Lets get back to prop walk, Then we can get back to some more rudder. -

Why not build the boat with the stuff tube slightly offset angled to the left to begin with. Still centered in the exit of the transom but with slight angle left. It wouldn't take much. That eliminates the need for any rudder input/or offset left in a straight line that only causes more drag anyway right ??

Now for heat racing rudders, we have established short isn't bad, too thin may be bad without above mentioned compensation or a properly tapered blade , yes ? How short is too short, and when do you know?? Using a tapered rudder for heat trim that is. Hows the boat gonna act when your close to too short??

Andy

 

[Andy Greene]

By the way- you dodged this question

From the sounds of your responses I would say the record boat had a VERY long strut in reference to distance from rudder leading edge ?? ?

 

[Ron Olson]

I noticed that so i'll try to fill in whqat we were talking about a lot earlier on page one.

We had problems with chine-walk and other things on a small mono. The 3/16" Speedmaster stinger strut and rudder were used on a 26" hull.

Ever ridden in a full-sized boat and looked over the transom at speed? I had forgotten all about this when dealing with a model boat. You know how the water reacts after coming off the trqansom? It rises up then vortexes behind the boat. When hanging a prop way back out there in that vortex we need to run the stinger higher up. When the strut is closer to the transom you can run it lower as the water hasn't had enough of a chance to rise back up yet.

I hope that this didn't confuse anyone as it wasn't easy for me to put into words.

 

[John Finch]

Andy,Should have been there man. The water was great. I think everyone would say a smaller and shorter rudder is the way to go because it's less drag. I feel that a wider rudder might sometimes be better than having to use trim tabs. I also think if your boat requires say 1/4th inch of left rudder to make the boat track straight. then a 1/4 inch rudder width with the right side of the blade parallel to the keel is better than a 1/8th thick blade that leaves a vapor trail on the right side of the rudder. And since the amount of rudder has a great deal with keeping the prop from dragging the transom to the left, it takes a certain amount of rudder to keep the boat tracking straight. What I try to keep in mind is that without a rudder the boat would do a big right hand turn. How much rudder you add to that equasion will directly affect how much control you have in keeping the boat in a straight line going down the straightaway.

So, in the last hour we have talked about rudder location as far as distance from the transom and how it trips the boat into pushing the bow down or lets the bow fly free, Thickness, rounding the bottom, position in relation to prop, How it can be a trim tab, How making travel less sensitive can prevent non linear turning, and how different setups work on different boats. That's pretty good. A lot of good input. There is also shape of rudder, pivot point, kicking it back vs tucking it in, tilting it to the right, and distance from the keel to the chine line. Who would have thought so much could be controlled by a simple rudder or combination of rudders.

Lets get back to prop walk, Then we can get back to some more rudder. -

Why not build the boat with the stuff tube slightly offset angled to the left to begin with. Still centered in the exit of the transom but with slight angle left. It wouldn't take much. That eliminates the need for any rudder input/or offset left in a straight line that only causes more drag anyway right ??

Now for heat racing rudders, we have established short isn't bad, too thin may be bad without above mentioned compensation or a properly tapered blade , yes ? How short is too short, and when do you know?? Using a tapered rudder for heat trim that is. Hows the boat gonna act when your close to too short??

Andy

Andy,

If you exit the stuffing tube in the center of the boat and then twist the strut to the left to compensate for prop walk a very bad thing happens. The prop is then to the left of centerline and that amplifies chine walk. To twist the strut to the left you must exit the transom way out to the right so the prop ends up to the right of centerline so as to prevent chine walk. Years ago we twisted the struts then the boats got violent on chine walk. You have to see the whole picture. As for strut length on the 20 mono. It was short, but I can't remember how short.

 

[John Finch]

By the way- you dodged this question
From the sounds of your responses I would say the record boat had a VERY long strut in reference to distance from rudder leading edge ?? ?

Yes, I am dodging the question. And yes.........I got off the subject as we were talking struts and stingers. They all work. It's where you mount them and how deep, angled, and long they are that make the difference.

 

[Andy Greene]

You mentioned rudder shapes. During an F/E saws I attended, there were several boats that were using modified kitchen knife blades. Very thin. I can see the advantage in SAWS how about oval trim ??

 

[John Finch]

You mentioned rudder shapes. During an F/E saws I attended, there were several boats that were using modified kitchen knife blades. Very thin. I can see the advantage in SAWS how about oval trim ??

That would be scary to think you are dragging a steak knife thru the water. You could catch and filet a fish at the same time. I have enough trouble trying to not get cut by my props.

 

[Andy Greene]

You mentioned rudder shapes. During an F/E saws I attended, there were several boats that were using modified kitchen knife blades. Very thin. I can see the advantage in SAWS how about oval trim ??

That would be scary to think you are dragging a steak knife thru the water. You could catch and filet a fish at the same time. I have enough trouble trying to not get cut by my props.

Hell on the turtles too- But they use em.

Okay , for heat racing trim, would the rudder that tappers in thickness front to rear be better served than say a rudder that is the same thickness front to rear ? what would the handleing differances be in oval trim ??

 

[John Finch]

You mentioned rudder shapes. During an F/E saws I attended, there were several boats that were using modified kitchen knife blades. Very thin. I can see the advantage in SAWS how about oval trim ??

That would be scary to think you are dragging a steak knife thru the water. You could catch and filet a fish at the same time. I have enough trouble trying to not get cut by my props.

Hell on the turtles too- But they use em.

Okay , for heat racing trim, would the rudder that tappers in thickness front to rear be better served than say a rudder that is the same thickness front to rear ? what would the handleing differances be in oval trim ??

I have used both with success, but with the stressors we have on our heat racing boats I feel a wedge rudder gives better stability.

 

[Ian Inverarity]

For my Seaducer I followed the given measurements and suggested hardware and it works well. Has someone found a better way to skin a cat-seaducer mono in this case- Using a stinger that works well on say a 40 or 60 Seaducer ??
Somewere I saw a REALLY trick adjusting device that worked on a strut- gave VERY accurate strut adjustments in height and pitch- just cant remember were !!!! <_<

What kind of effect would we have if the rudder was run even further in(closer to the transom) than than in-line idea ??(leading edge of rudder with leading edge of prop surface) Would the boat be tighter due to the rudder being closer to the transom ?

What about sharpening the bottom of the rudder blade to a sharp edge rather than a flat bottom? benefits? downsides?

Andy

I have found a profound difference in location of rudder on the transom affecting almost every aspect in trimming the boat. The 77 mph pass KP and I did with the 20 mono at record trials is a good example. The rudder was used to tune the boat for the correct ride. The distance from the transom was paramount in trimming the boat because there were no trim tabs. If I told you the strut length you would say...........no way. Don't even ask. As for todays heat racing boats You are totally correct on the rudder location as far as distance from the transom. The closer the rudder is to the transom, the more it holds the bow down. As you move the rudder away from the transom the nose ( bow) becomes lighter on the water. As for the bottom of the rudder...........if it's flat it can lift the boat like a riding surface, so rounding it off is usually a good idea.

John

John,

How does the rudder being closer to the transom hold the bow down? I would have thought that with the boat heeled over into the turn, the heeled over rudder as well would provide some lift, and the futher back from the transom the more leverage the lift would have? :huh: I am not saying that is doesnt work, I am trying to understand why it works!

I am trying to trim my CMB101 powered mono to be better in turns. Currently the boat rides too loose thru the turns with my favourite prop. If I put the strut down to trim the boat wetter in the straights the deeper strut has the opposite effect in turns and the boat rides looser in turns. I dont understand why the strut depth has opposite effects on the straights and turns and wonder if it may be related to the effect where the rudder closer to the transom holds the bow down?

Ian.

 

[John Finch]

For my Seaducer I followed the given measurements and suggested hardware and it works well. Has someone found a better way to skin a cat-seaducer mono in this case- Using a stinger that works well on say a 40 or 60 Seaducer ??
Somewere I saw a REALLY trick adjusting device that worked on a strut- gave VERY accurate strut adjustments in height and pitch- just cant remember were !!!! <_<

What kind of effect would we have if the rudder was run even further in(closer to the transom) than than in-line idea ??(leading edge of rudder with leading edge of prop surface) Would the boat be tighter due to the rudder being closer to the transom ?

What about sharpening the bottom of the rudder blade to a sharp edge rather than a flat bottom? benefits? downsides?

Andy

I have found a profound difference in location of rudder on the transom affecting almost every aspect in trimming the boat. The 77 mph pass KP and I did with the 20 mono at record trials is a good example. The rudder was used to tune the boat for the correct ride. The distance from the transom was paramount in trimming the boat because there were no trim tabs. If I told you the strut length you would say...........no way. Don't even ask. As for todays heat racing boats You are totally correct on the rudder location as far as distance from the transom. The closer the rudder is to the transom, the more it holds the bow down. As you move the rudder away from the transom the nose ( bow) becomes lighter on the water. As for the bottom of the rudder...........if it's flat it can lift the boat like a riding surface, so rounding it off is usually a good idea.

John

John,

How does the rudder being closer to the transom hold the bow down? I would have thought that with the boat heeled over into the turn, the heeled over rudder as well would provide some lift, and the futher back from the transom the more leverage the lift would have? :huh: I am not saying that is doesnt work, I am trying to understand why it works!

I am trying to trim my CMB101 powered mono to be better in turns. Currently the boat rides too loose thru the turns with my favourite prop. If I put the strut down to trim the boat wetter in the straights the deeper strut has the opposite effect in turns and the boat rides looser in turns. I dont understand why the strut depth has opposite effects on the straights and turns and wonder if it may be related to the effect where the rudder closer to the transom holds the bow down?

Ian.

Ian,

Let me try to explain...........If the rudder is close to the transom it trips the boat like a trim tab and pushes the bow down. If it is far away from the transom it just drags behind the boat. The best way to imagine what is happening is to over exagerate the conditions. Imagine the rudder is 3 feet from the transom. That's pretty imaginative. If you could to grab the rudder while the boat was running the boat would simply stop moving forward. It would not trip. Just like trim tabs three feet behind the boat would just be metal dragging in the water. Where the rudder has more leverage is when it is mounted further back from the turn fin. And that leverage is in turning the hull in relation to the turn fin. So, if you change the rudder location for one reason, it also affects other handling characteristics. If you have a boat that does well in the straights but breaks loose in the corners there are a bunch of things that come into play. A photo of the transom would be of great help in seeing how the variables are laid out.